/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.wal.utils;

import java.io.File;
import java.util.Arrays;
import java.util.Comparator;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static org.apache.iotdb.commons.conf.IoTDBConstant.*;

public class CheckpointFileUtils {
    /**
     * versionId is a self-incremented id number, helping to maintain the order of checkpoint files
     */
    public static final Pattern CHECKPOINT_FILE_NAME_PATTERN =
            Pattern.compile(
                    String.format(
                            "%s(?<%s>\\d+)\\%s$", WAL_FILE_PREFIX, WAL_VERSION_ID, WAL_CHECKPOINT_FILE_SUFFIX));

    /**
     * Return true when this file is .checkpoint file
     */
    public static boolean checkpointFilenameFilter(File dir, String name) {
        return CHECKPOINT_FILE_NAME_PATTERN.matcher(name).find();
    }

    /**
     * List all .checkpoint files in the directory
     */
    public static File[] listAllCheckpointFiles(File dir) {
        return dir.listFiles(CheckpointFileUtils::checkpointFilenameFilter);
    }

    /**
     * Parse version id from filename
     */
    public static int parseVersionId(String filename) {
        Matcher matcher = CHECKPOINT_FILE_NAME_PATTERN.matcher(filename);
        if (matcher.find()) {
            return Integer.parseInt(matcher.group(WAL_VERSION_ID));
        }
        throw new RuntimeException("Invalid checkpoint file name: " + filename);
    }

    /**
     * Sort checkpoint files by version id with descending order *
     */
    public static void descSortByVersionId(File[] checkpointFiles) {
        Arrays.sort(
                checkpointFiles,
                Comparator.comparingInt(file -> parseVersionId(((File) file).getName())).reversed());
    }

    /**
     * Get .checkpoint filename
     */
    public static String getLogFileName(long version) {
        return WAL_FILE_PREFIX + version + WAL_CHECKPOINT_FILE_SUFFIX;
    }
}
